This article proposes how language relates structurally and evolutionarily to cognition. It heuristically divides cognition into cognitive systems and the organizing factors that structure them. The general finding is that cognitive systems share these structural properties to different degrees. This is termed the “overlapping systems model of cognitive organization”. The specific finding is that the cognitive system of language shares many structural properties with the cognitive systems of visual perception, of somatosensory perception and motor control, and of understanding, but shares few structural properties with those of affect and of culture.